I've installed the nginx-light package on debian, but I can't find the executable. It's not in
/usr/bin, like it says on the official nginx website. Where is it, then?
To get a list of all the files installed by a package, you can use
dpkg -L <package_name>
In your case
dpkg -L nginx-light
will list all the files installed by the package. Look at that list to know where the executable has been installed. Also, if you know the executable's name beforehand, you can filter the list of files with
dpkg -L nginx-light | grep '.*/nginx$'
nginx above by the actual name of the